Display having light-scattering property

ABSTRACT

A display includes light-scattering regions. Each of the light-scattering regions is provided with linear protrusions and/or recesses having the same longitudinal direction. The light-scattering regions are different from each other in the longitudinal direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/619,558, filed Feb. 11, 2015, which is a continuation of U.S. patentapplication Ser. No. 12/801,635, filed Jun. 17, 2010 and which is acontinuation Application of PCT Application No. PCT/JP2008/057611, filedApr. 18, 2008, which was published under PCT Article 21(2) in Japanese,the contents of all of the above being incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a display and a labeled article. Thisinvention relates to, for example, a display which can be used forforgery-prevention of articles such as cards, securities and brand-nameproducts and which displays an image by utilizing light-scattering, andto a labeled article including it.

2. Description of the Related Art

Generally, a pattern for displaying an image by light-scattering(hereinafter called a light-scattering pattern) is formed by subjectinga surface of a substrate to a relief-processing. The relief-processingmethod includes, for example, a method of etching a substrate, a methodof roughening a surface of a substrate with a chemical, a method offorming relief on a surface of a substrate using an EB writer, or thelike.

Among these method, according to the method utilizing etching and themethod using a chemical, it is difficult to make a density of recessesand/or protrusions in a certain fine region different from that inanother fine region, on a surface where the recesses and/or protrusionsare to be formed. It is therefore difficult to make the degrees ofscattering in those regions different from each other by controlling thedensities of the recesses and/or protrusions. On the other hand, if theEB writer is used, the densities and shapes of recesses and/orprotrusions to be formed in the fine regions can be controlledarbitrarily.

Jpn. Pat. Appln. KOKAI Publication No. 5-273500 describes a display onwhich a diffraction grating pattern and a light-scattering pattern areformed in the same surface using an EB writer. This display has thefollowing effects.

(a) Since display does not rely on diffracted light alone, restrictionson observation conditions are small.

(b) Since the scattered light is also used for the display, aniridescent appearance is not the only impression that the image offers.

(c) Since both the diffraction grating pattern and the light-scatteringpattern are constituted by the recesses and/or protrusions, thosepatterns can be formed by embossing and the alignment between thosepatterns is unnecessary.

However, a relief-type diffraction grating can be formed with relativeease by laser facilities, etc. In addition, a visual effect of thelight-scattering pattern included in the above display can be obtainedfrom, for example, a printed layer containing transparent particles andtransparent resin having a refractive index different from that of thetransparent particles. For this reason, the forgery-prevention effect ofthis display is not always considered sufficient.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to realize a forgery-preventiontechnique for achieving a high forgery-prevention effect.

According to a first aspect of the invention, there is provided adisplay comprising light-scattering regions each provided with linearprotrusions and/or recesses having the same longitudinal direction, thelight-scattering regions being different from each other in thelongitudinal direction.

According to a second aspect of the invention, there is provided alabeled article comprising the display according to the first aspect,and an article supporting the display.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a plan view schematically showing a display according to afirst embodiment of the present invention;

FIG. 2 is a schematic sectional view taken along the line II-II of thedisplay shown in FIG. 1;

FIG. 3 is a view showing an example of a relationship betweenillumination light incident on a diffraction grating and diffractedlight emitted from the diffraction grating;

FIG. 4 is a plan view schematically showing an example of alight-scattering region;

FIG. 5 is a plan view showing an example of a structure which can beemployed in the light-scattering region;

FIG. 6 is a plan view showing another example of a structure which canbe employed in the light-scattering region;

FIG. 7 is a plan view showing another example of a structure which canbe employed in the light-scattering region;

FIG. 8 is a plan view showing another example of a structure which canbe employed in the light-scattering region;

FIG. 9 is a plan view showing another example of a structure which canbe employed in the light-scattering region;

FIG. 10 is a plan view schematically showing a display according to asecond embodiment of the present invention;

FIG. 11 is a plan view schematically showing a modification of thedisplay shown in FIG. 10;

FIG. 12 is a perspective view schematically showing an example of alight-scattering region including protrusions and/or recesses having ashape other than a linear shape;

FIG. 13 is a perspective view schematically showing another example of alight-scattering region including protrusions and/or recesses having ashape other than a linear shape; and

FIG. 14 is a plan view schematically showing an example of an articlewhich supports a display.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below withreference to the accompanying drawings. The same reference symbolsdenote components having the same or similar functions throughout all ofthe drawings and their duplicated descriptions will be omitted.

FIG. 1 is a plan view schematically showing a display according to afirst embodiment of the present invention. FIG. 2 is a schematicsectional view taken along the line II-II of the display shown in FIG.1.

A display 1 contains a layer 2. The layer 2 includes, for example, alight-transmitting material layer 50 and a reflective material layer 51.As shown in FIG. 2, an adhesive layer 52 can be provided on a surface ofthe reflective material layer 51 which is on an opposite side to thelight-transmitting material layer 50. In an example shown in FIG. 2, aside on the light-transmitting material layer 50 is a front side and aside on the adhesive layer 52 is a back side.

The reflecting material layer 51 covers a back of the light-transmittingmaterial layer 50. A relief structure is provided to an interfacebetween the light-transmitting material layer 50 and the reflectingmaterial layer 51. The relief structure will be described later. Itsuffices that the reflecting material layer 51 covers at least a regionof the interface of the light-transmitting material layer 50 used fordisplaying an image by the relief structure. The adhesive layer 52 isprovided on the reflecting material layer 51.

The light-transmitting material layer 50 plays a role as, for example,an underlayer of the reflecting material layer 51. Thelight-transmitting material layer 50 also plays a role of protecting therelief structure from contamination, flaw, etc. of the surface andthereby maintaining the visual effect of the display 1 for a longperiod. Furthermore, the light-transmitting material layer 50 preventsthe relief structure from being exposed and makes its duplicationdifficult. Either of the light-transmitting material layer 50 and thereflecting material layer 51 may be omitted. In a case where thereflecting material layer 51 is omitted, in order that light reflects onthe interface between the light-transmitting material layer 50 and theadhesive layer 52, it is good to make the difference in refractive indexbetween the light-transmitting material layer 50 and the adhesive layer52 greater or to form the adhesive layer 52 of a material having thereflectivity.

As the material of the light-transmitting material layer 50,thermoplastic resin, ultraviolet curing resin, etc. are suitable to forma relief structure by transfer using the master. In a case of usingembossing, if the relief structure corresponding to a diffractiongrating region 10 and light-scattering regions 20 a and 20 b to bedescribed later is formed on the master with high accuracy, precisemass-produced copies can be easily obtained.

A structure of two or more layers may be employed for thelight-transmitting material layer 50, in consideration of the surfacestrength and the ease of formation of the relief structure. In addition,in a case where metal is used as the material of the reflecting materiallayer 51, it is also possible to blend dye, etc. with the lighttransmitting material layer 50 and make the dye absorb light of aspecific wavelength, to change a metallic luster color derived from themetal to a color different therefrom.

The reflecting material layer 51 plays a role of increasing thereflectivity of the interface where the relief structure is provided. Asthe material of the reflecting material layer 51, for example, metalmaterials such as Al, Ag, etc. can be used. In addition, the material ofthe reflecting material layer 51 may be a transparent material such as adielectric material, etc. which has a refractive index different fromthat of the light-transmitting material layer 50. The reflectingmaterial layer 51 may not only be a single layer, but also amultilayered film.

The adhesive layer 52 is provided to attach the display 1 to an articlewhose forgery should be prevented. The adhesive layer 52 may be formedof two or more layers, in consideration of the adhesive strength betweenthe display 1 and the article whose forgery should be prevented,smoothness of the adhesive surface, etc.

FIG. 2 shows the structure of the display 1 to be observed from the sideon the light-transmitting material layer 50, but the structure of thedisplay 1 to be observed from the side on the reflecting material layer51 can also be employed.

Next, the relief structure provided on the layer 2 will be described.

The layer 2 includes the diffraction grating region 10, the firstlight-scattering region 20 a, the second light-scattering region 20 b,and a region 30.

In the diffraction grating region 10, a diffraction grating patternconstituted by relief-type diffraction grating is formed on theinterface between the light-transmitting material layer 50 and thereflecting material layer 51. The diffraction grating is constituted by,for example, arraying grooves. The term “diffraction grating” means astructure in which a diffracted wave is generated by radiatingillumination light, and encompasses not only general diffraction gratingin which, for example, grooves are arranged parallel at regularintervals, but also interference fringes recorded in a hologram. Inaddition, the groove or a portion sandwiched by the grooves is called“grating line”.

A depth of the grooves forming the diffraction grating is set to bewithin a range of, for example, 0.1 to 1 μm. In addition, a gratingconstant of the diffraction grating is set to be within a range of, forexample, 0.5 to 2 μm.

In each of the light-scattering regions 20 a and 20 b, linearprotrusions and/or recesses aligned in similar directions are providedon the interface between the light-transmitting material layer 50 andthe reflecting material layer 51. The directions of the linearprotrusions and/or recesses in the region 20 a are different from thatin the region 20 b.

If the region 20 a or 20 b is illuminated from a direction normal to theregion, the region emits the scattered light with the widest angularrange of emission, i.e., with the widest range of angle of divergence,in a plane perpendicular to the longitudinal direction of the linearprotrusions and/or recesses, and emits the scattered light with thenarrowest angular range of emission, in a plane which is parallel to thelongitudinal direction of the linear protrusions and/or recesses andwhich is perpendicular to a main surface of the region. The angularrange within which the light-scattering region emits the scattered lightat a certain intensity or higher is hereinafter expressed by a term“light-scattering ability”. In a case where, for example, the term“light-scattering ability” is used, the above optical characteristic canbe described as “each of the regions 20 a and 20 b shows the minimumlight-scattering ability in the longitudinal direction of the linearprotrusions and/or recesses and shows the maximum light-scatteringability in the direction perpendicular thereto”. In addition, acharacteristic that a difference between the maximum light-scatteringability and the minimum light-scattering ability is sufficiently largeis called “anisotropic light-scattering ability”.

The length of the linear protrusions and/or recesses is set to be, forexample, 10 μm or more. The width of the protrusions and/or recesses isset to be, for example, within a range of 0.1 to 10 μm. The height ordepth of the protrusions and/or recesses is set to be, for example,within a range of 0.1 to 10 μm.

In the region 30, the relief structure is not provided on the interfacebetween the light-transmitting material layer 50 and the reflectivematerial layer 51. In other words, the interface between thelight-transmitting material layer 50 and the reflecting material layer51 is flat in the region 30.

The layer 2 can be constituted by, for example, segments correspondingto the regions 10, 20 a, 20 b and 30, respectively. Alternatively, thelayer 2 may be constituted by cells arrayed in a matrix, the diffractiongrating region 10 may be constituted by some of the cells, the region 20a may be constituted by some of the other cells, the region 20 b may beconstituted by some of the other cells, and the region 20 b may beconstituted of the remaining cells. In a case where the layer 2 isconstituted by cells, an image can be displayed by using each of thosecells as a pixel. The cells constituting the diffraction grating region10 are hereinafter called “diffraction grating cells” and the cellsconstituting the regions 20 a and 20 b are hereinafter called“light-scattering cells”.

In a case where the layer 2 is constituted by various types of cells, animage to be obtained by rearranging the cells can easily be expected ifthe visual effect of each of the cells is understood. For this reason,the cell to be used in each pixel can be easily determined from thedigital image data. In this case, the display 1 can easily be thereforedesigned.

To make the visual effects of the segments or of the pixels differentfrom each other, matters described below can be utilized.

First, the visual effect offered by the diffraction grating region 10will be described with reference to the drawings.

FIG. 3 is a view showing an example of a relationship between theillumination light incident on a diffraction grating and the diffractedlight emitted from the diffraction grating.

If illumination light 71 is made incident on diffraction grating 11 atan angle of incidence a′ in a direction perpendicular to the gratinglines, the diffraction grating 11 emits first-order diffracted light 73,which is typical diffracted light, at an angle of emergence β. Areflection angle or an angle of emergence α of light regular-reflectedby the diffraction grating 11 (0-order diffracted light) 72 is equal tothe incident angle α′ in terms of absolute value, and symmetricalthereto about the normal line (for α, β, the clockwise direction is thepositive direction). The angle α and the angle β fulfill a relationshiprepresented in the following equation (1) where the grating constant ofthe diffraction grating 11 is d (nm) and the wavelength of theillumination light 71 is λ (nm).

d=λ/(sin α−sin β)  (1)

As will be apparent from the above equation (1), if white light is madeincident, the angle of emergence of the first-order diffracted lightvaries according to the wavelength. In other words, the diffractiongrating 11 has a function of a spectroscope, and a color of thediffraction grating region 10 is changed iridescently when the positionof observation is changed.

In addition, the color seen by an observer under a certain observationcondition is changed according to the grating constant d.

For example, it is assumed that the diffraction grating 11 emits thefirst-order diffracted light 73 in a direction perpendicular to a planeof the grating. In other words, it is assumed that the angle β ofemergence of the first-order diffracted light 73 is 0°. In this case, ifthe absolute values of the incident angle of the illumination light 71and the angle of emergence of the 0-order diffracted light 72 are α_(N),the equation (1) is simplified as follows.

d=λ/sin α_(N)  (2)

As will be apparent from the equation (2), in order to make the observersee a certain color, the wavelength λ corresponding to the color, theabsolute value α_(N) of the incident angle of the illumination light 71,and the grating constant d may be set to fulfill the relationshiprepresented by the equation (2). For example, if the white lightincluding rays having wavelengths of 400 to 700 nm is the illuminationlight 71, the absolute value α_(N) of the incident angle of theillumination light 71 is 45°, and a diffraction grating in which aspatial frequency of diffraction grating, i.e., an inverse of thegrating constant ranges from 1,800 to 1,000/mm is used, the portion atwhich the spatial frequency is approximately 1,600/mm is seenblue-colored and the portion at which the spatial frequency isapproximately 1,100/mm is seen red-colored. Therefore, by making thespatial frequencies of the diffraction gratings different between thesegments or the cells, their display colors can be made different fromeach other.

The smaller the spatial frequency of the diffraction grating is, theeasier the formation of the diffraction grating is. For this reason, thespatial frequency is set to be 500 to 1,600/mm in many of the generaldiffraction gratings used for the display.

In the above descriptions, it is assumed that the illumination light 71is made incident on the diffraction grating 11 in the directionperpendicular to the grating lines. In such a situation, when thediffraction grating 11 is rotated around its normal line with thedirection of observation unchanged, an effective value of the gratingconstant d is changed according to the rotation angle. As a result, thecolor seen by the observer is changed. If the rotation angle issufficiently great, the observer can not see the diffracted light in theabove direction of observation. For this reason, by making the segmentsor the cells have different orientations of the grating lines, theirdisplay colors can be made different from each other, and the directionin which the cells are seen brightly due to the diffracted light can bechanged.

In addition, the diffraction efficiency is changed by making the depthsof the grooves constituting the diffraction grating 11 great. And, thegreater the area ratio of the diffraction grating with respect to thesegments or cells is made, the greater the intensity of the diffractedlight is.

Therefore, if the segments or cells are made to have different spatialfrequencies and/or orientations of the diffraction grating, the colorsdisplayed on the segments or cells can be made different from eachother, and the conditions permitting the observation can be adjusted.Further, if the segments or cells are made different in at least one ofthe depths of the grooves forming the diffraction grating 11 and thearea ratios of the diffraction grating 11 with respect to the segmentsor cells, the segments or cells can be made different in brightness. Forthis reason, by utilizing these, an image such as a full-color image, astereoscopic image, etc. can be displayed.

Next, visual effects offered by the light-scattering regions 20 a and 20b will be described with reference to the drawings.

FIG. 4 is a plan view schematically showing an example of alight-scattering region.

A light-scattering region 20 shown in FIG. 4 includes light-scatteringstructures 25. The light-scattering structures 25 are protrusions and/orrecesses each having a linear shape and aligned in same directions ineach light-scattering region 20. In other words, the light-scatteringstructures 25 are aligned substantially parallel with each other in eachlight-scattering region 20.

It is not necessary that the light-scattering structures 25 are alignedcompletely parallel with each other in each light-scattering region 20.As long as the light-scattering region 20 has a sufficient anisotropiclight-scattering ability, for example, the longitudinal direction ofsome of the light-scattering structures 25 may cross the longitudinaldirection of the other light-scattering structures 25 in thislight-scattering region 20. Among directions parallel to the mainsurface of the light-scattering region 20, a direction in which thelight-scattering region 20 represents a minimum light-scattering abilityis hereinafter called “an orientational direction” and a direction inwhich the light-scattering region 20 represents a maximumlight-scattering ability is hereinafter called “a light-scatteringaxis”. In the present embodiment, since the basic structure is thelinear structure, the orientational direction is orthogonal to thelight-scattering axis.

In the light-scattering region 20 shown in FIG. 4, a direction denotedby arrow 26 is the orientational direction and a direction denoted byarrow 27 is the light-scattering axis. For example, when thelight-scattering region 20 is illuminated in an oblique directionperpendicular to the orientational direction 26 and thislight-scattering region 20 is observed from the front with an unaidedeye, the light-scattering region 20 is seen comparatively brightly dueto its high light-scattering ability. On the other hand, when thelight-scattering region 20 is illuminated in an oblique directionperpendicular to the light-scattering axis 27 and this light-scatteringregion 20 is observed from the front with an unaided eye, thelight-scattering region 20 is seen comparatively darkly due to its lowlight-scattering ability.

As will be apparent from above, for example, in a case where thelight-scattering region 20 is illuminated in the oblique direction andthis is observed from the front with an unaided eye, as thelight-scattering region 20 is rotated about its normal line, brightnessthereof is changed. For this reason, for example, if the same structuresare employed in the light-scattering region 20 a and thelight-scattering region 20 b shown in FIG. 1 and only a direction of thelight-scattering axis in region 20 a is made different from that of thelight-scattering axis in region 20 b, the region 20 b is seencomparatively darkly when the region 20 a is seen most brightly, and theregion 20 b is seen comparatively brightly when the region 20 a is seenmost darkly. In addition, the region 20 a is seen comparatively darklywhen the region 20 b is seen most brightly, and the region 20 a is seencomparatively brightly when the region 20 b is seen most darkly.

In other words, by making the light-scattering axis 27 in the region 20a different from that of the region 20 b, difference in brightnessbetween them can be caused. Therefore, an image can be therebydisplayed. In particular, by making an angle formed by thelight-scattering axis 27 in the region 20 a and that of the region 20 bsufficiently great (for example, 30° or greater in a typical room inwhich illumination light sources are arranged on a ceiling, whichdepends the magnitude of the illumination light sources) or by makingeach anisotropic light-scattering ability sufficiently great, the imagesdisplayed on the respective regions can be observed with an unaided eyeunder different observation conditions. By employing thelight-scattering structures in which the light-scattering axes areorthogonal to each other, similarly to the light-scattering regions 20 aand 20 b, the conditions for observing the images displayed on therespective regions are completely made different from each other, andthe images can be certainly observed separately.

The brightness of the light-scattering region 20 can also be controlledin other manners.

For example, the greater the width of the light-scattering structures 25is, the smaller the light-scattering ability in the direction of thelight-scattering axis 27 is. On the other hand, the longer thelight-scattering structures 25 are, the smaller the light-scatteringability in the orientational direction 26 is.

All the light-scattering structures 25 in a single light-scatteringregion 20 may have the same shape. Alternatively, protrusions and/orrecesses 25 having different shapes may be present in a single lightscattering-region 20.

When the light-scattering region 20 include only the light-scatteringstructures 25 having the same shape, the light-scattering ability can bedesigned easily. In addition, such a light-scattering region 20 can beformed with high accuracy and ease by using a fine processing devicesuch as an EB writer, stepper, etc. On the other hand, when thelight-scattering region 20 includes the light-scattering structures 25having different shapes, scattered light having a gentle distribution oflight intensity over a wide angular range can be obtained. For thisreason, white color can be displayed stably with reduced variations oflight-and-shade according to the observation position.

In addition, the higher the degree of orientational order of thelight-scattering structures 25 is, the greater the anisotropiclight-scattering ability of the light-scattering region 20 is.

In the light-scattering region 20, the light-scattering structures 25may be arranged regularly to some extent or randomly. For example, ifintervals of the light-scattering structures 25 in a direction parallelto the light-scattering axis 27 are set randomly, the light-intensitydistribution of the scattered light in a direction perpendicular to theorientational direction 26 is gentle. Therefore, variation in whitenessand brightness according to the observation angle is restricted.

If the intervals among the light-scattering structures 25 in thedirections parallel to the-light scattering axis 27 are made smaller,much more incident light can be scattered, and the intensity of thescattered light can be therefore made greater without degrading theanisotropic light-scattering ability. For example, if the averageinterval among the light-scattering structures 25 in the directionparallel to the light-scattering axis 27 is 10 μm or smaller, it ispossible to obtain the light-scattering intensity sufficient to displayan image with good visibility.

In a case where the light-scattering region 20 is constituted bylight-scattering cells, if this average interval is made sufficientlysmall, it is sufficiently possible to set the size of thelight-scattering cells at approximately 100 μm. In this case, images canbe displayed with resolution equal to or higher than that of a human eyeunder general observation conditions. In other words, images withsufficiently high-resolution can be displayed.

Although two light-scattering regions 20 a and 20 b having thelight-scattering axes approximately orthogonal to each other arearranged in FIG. 1, three or more light-scattering regions havinglight-scattering axes different from one another may be arranged.

FIGS. 5 to 7 are plan views showing examples of structures which can beemployed in the light-scattering regions. In FIGS. 5 to 7, each whiteportion corresponds to a protrusion or a recess.

In the light-scattering region 20 shown in FIG. 5, the light-scatteringstructures 25 are oriented in y direction. In the light-scatteringregion 20 shown in FIG. 6, the light-scattering structures 25 areoriented in a direction that forms an angle of 45° in counterclockwisedirection with respect to the y direction. In the light-scatteringregion 20 shown in FIG. 7, the light-scattering structures 25 areoriented in x direction orthogonal to the y direction.

Thus, if three or more light-scattering regions having light-scatteringaxes different from each other are arranged, for example, gradation canbe displayed and the image change due to the change in the orientationof the display 1 can be made more complicated. For example, it is alsopossible to change the image as animation by changing the orientation ofthe display 1.

FIGS. 8 and 9 are plan views showing other examples of the structurewhich can be employed in the light-scattering region.

In the light-scattering region 20 shown in FIG. 8, the light-scatteringstructures 25 are oriented in y direction. In the light-scatteringregion 20 shown in FIG. 9, the light-scattering structures 25 areoriented in x direction.

The light-scattering structures 25 shown in FIGS. 8 and 9 are wider thanthe light-scattering structures 25 shown in FIGS. 5 to 7. Therefore, thedegree of divergence of the scattered light emitted from thelight-scattering region 20 shown in FIGS. 8 and 9 in the directionperpendicular to the orientational direction 26 is lower than that ofthe scattered light emitted from the light-scattering region 20 shown inFIGS. 5 to 7.

In a case where the degree of divergence of the scattered light is low,the intensity of the scattered light observed at a specific position ishigh. Thus, an image formed by regions which have the same directions ofthe light-scattering axes 26 and have widths of the light-scatteringstructures 25 different from each other, for example, thelight-scattering region 20 shown in FIG. 5 and the light-scatteringregion 20 shown in FIG. 8, is seen as an image with light and shade whenobserved at a predetermined position.

The light-scattering regions 20 a and 20 b shown in FIGS. 1 and 2 arenot limited to the light-scattering regions 20 shown in FIGS. 5 to 7 andFIGS. 8 and 9, but may employ various structures.

As described above, the images displayed on the light-scattering regions20 a and 20 b shown in FIG. 1 have a clear switching effect. In otherwords, two images displayed by two light-scattering regions 20 a and 20b having light-scattering axes 27 different from each other are not seenas a single image, but can be clearly observed separately with anunaided eye. In addition, by providing the light-scattering regions 20having light-scattering axes 27 different from each other, the samenumber of images as that of the provided light-scattering axes 27 can bedisplayed on the display 1. Thus, similar to an animation, an image canalso be changed according to the change of the observation position.

The light-scattering structures 25 may have binary structures or mayhave continuously-varying structures in the depth or height direction.

The light-scattering region 20 including the light-scattering structures25 having the binary structures can be produced with relative ease by adevice having a fine processing ability, and a shape thereof, etc. canalso be set easily. The light-scattering region 20 including thelight-scattering structures 25 of the continuously-varying structurescan be easily produced by recording a speckle in a photosensitivematerial, for example, photoresist by using the interference of thelaser beam. When the area of the portion provided with thelight-scattering structures 25 is 50% of the area of thelight-scattering region 20 in the case of the binary structure, oralternatively when the area of the portion provide with thelight-scattering structure 25 is 100% of the area of thelight-scattering region 20, i.e., no flat surface is present in the caseof the continuously-varying structure, the light-scattering structure inthe light scattering region 20 has the highest scattering efficiency.

The layer 2 of the display 1 shown in FIGS. 1 and 2 includes twolight-scattering regions 20 a and 20 b having light-scattering axesdifferent from each other. The light-scattering region 20 a displays aletter “9” as an image, while the light-scattering region 20 b displaysa marginal part of the letter “9” as an image.

In the display 1 shown in FIG. 1, the light-scattering axis of theregion 20 a is orthogonal to that of the region 20 b. As describedabove, when the light-scattering region 20 a or 20 b is observed from adirection perpendicular to the orientational direction 26, a brightimage can be seen irrespective of the observation angle since thedisplay light is divergent. Therefore, if the display 1 is observed fromthe direction perpendicular to the orientational direction 26 of thelight-scattering region 20 a, the letter “9” alone is seen whitish andthe marginal part thereof is seen darkly. On the other hand, if thedisplay 1 is observed from the direction perpendicular to theorientational direction 26 of the light-scattering region 20 b, themarginal part of the letter “9” alone is seen whitish. In other words,the light-and-shade of the light-scattering regions 20 a and 20 b isreversed according to the orientation of display 1, since the display 1shown in FIG. 1 includes two light-scattering regions 20 a and 20 bhaving light-scattering axes different from each other.

Since the display 1 shown in FIGS. 1 and 2 includes two light-scatteringregions 20 a and 20 b having light-scattering axes 27 whose directionsare different from each other, predetermined images can be observed fromdifferent directions corresponding to the scattering axes, respectively.Although the similar change of the observed image according to theobservation positions can be achieved by the diffraction grating region10, substantially uniform white, unlike the iridescent appearance of thediffraction grating region 10, can be seen in a comparatively wide rangeof the observation positions.

In the above description, the white scattered light is described byexemplifying a case where the transmitting material layer 50 shown inFIG. 2 does not have a specific absorption band in the visible region.If the transmitting material layer 50 contains dye, etc., the scatteredlight from the light-scattering region 20 is the scattered light ofwavelength components which pass through the transmitting material layer50.

The display 1 shown in FIGS. 1 and 2 further includes the region 30 inwhich relief structures are not provided, besides the diffractiongrating region 10 and the light-scattering regions 20 a and 20 b. Theimage observed on the region 30 is not changed even if the observationposition is changed, except the position at which the regular-reflectedlight is observed. If the layer 2 is constituted by the transmittingmaterial layer 50 and the reflecting material layer 51 shown in FIG. 2,the region 30 has a metallic appearance of the reflecting material layer51.

In other words, the display 1 shown in FIGS. 1 and 2 has the complicatedvisual effects since the display 1 combines the diffraction gratingregion 10 which has a visual effect of greatly changing the appearanceof the images according to the observation position, twolight-scattering regions 20 a and 20 b which have the light-scatteringaxis 27 orthogonal to each other and have the image-switching effect andthe stable observation effect, and the region 30 whose appearance is notchanged according to the viewpoint. Furthermore, the display 1 shown inFIGS. 1 and 2 has further complicated visual effects as compared with adisplay which displays an image using either the diffraction gratingregion 10 or the light-scattering regions 20 a and 20 b, since theimages are displayed separately on the respective regions. Therefore,distinction from an imitation can be executed with extremely ease andcertainty, and the forgery-prevention effect is thereby enhanced.

The display 1 shown in FIGS. 1 and 2 can display various imagesdifferent in color, brightness, etc. by arbitrarily designing each ofthe diffraction grating region 10 and the light-scattering regions 20 aand 20 b. Therefore, the diffraction grating region 10 and thelight-scattering regions 20 a and 20 b can be designed in accordancewith the colors and brightness of the images to be displayed. Inaddition, since the diffraction grating 11 and the light-scatteringstructures 25 are constituted by protrusions and recesses in the display1 shown in FIGS. 1 and 2, the display 1 can be produced precisely andeasily by merely duplicating the protrusions and recesses whilemaintaining the structures, positional relationship and functionsthereof. The display 1 produced with high accuracy has the enhancedreliability on the display as a genuine article, and the certainty ofthe authenticity check thereof is enhanced.

Since the display 1 shown in FIGS. 1 and 2 includes the diffractiongrating region 10 and the light-scattering regions 20 a and 20 b, theappearance of images is changed according to the observation position.This visual effect cannot be reproduced by color copying of the display1. In addition, even if the display 1 shown in FIGS. 1 and 2 is to beforged or imitated, the precise relief structure having two differenttypes of effects can hardly be reproduced exactly. Moreover, thelight-scattering structure of the display 1 shown in FIGS. 1 and 2cannot be duplicated by an optical duplication method using thediffracted light from the diffraction grating 11.

Thus, due to the characteristic visual effects and the difficulty inforgery and imitation, the display 1 shown in FIGS. 1 and 2 can beapplied to, for example, securities, cards, passports, etc. as a highsecurity optical medium whose authenticity check can be easily executed.

In the display 1 shown in FIGS. 1 and 2, the diffraction grating region10 can be omitted. The display in which the diffraction grating region10 is omitted has complicated visual effects since the display combinestwo light-scattering regions 20 a and 20 b which have theimage-switching effect and the stable observation effect, and the region30 whose appearance is not changed according to the viewpoint. Thisdisplay has more complicated visual effects than a display whichdisplays an image using one light-scattering region 20 a or 20 b, sincethe images are displayed separately in the respective regions.Therefore, distinction from an imitation can be executed with extremelyease and accuracy, and the forgery-prevention effect is therebyenhanced.

Next, another embodiment of the present invention will be described.

FIG. 10 is a plan view schematically showing a display according to asecond embodiment of the present invention.

The display 1 shown in FIG. 10 is the same as the display 1 describedwith reference to FIGS. 1 and 2, except for employing the followingstructure. In the display 1 shown in FIG. 10, each of the diffractiongrating region 10 and the light-scattering regions 20 a and 20 b isconstituted by cells arrayed in matrix. In other words, in the display 1shown in FIG. 10, cells as pixels display images in each of the regions.

In the display 1 shown in FIG. 10, the diffraction grating region 10includes diffraction grating cells 12 a to 12 f having orientationsdifferent from one another.

Since the diffraction grating cells denoted by the same reference numberin FIG. 10 are substantially the same in orientation of diffractiongrating, the diffraction grating cells emit diffracted light accordingto the respective orientation. Therefore, the diffraction grating cellsdenoted by the same reference number display an image as pixels havingthe same visual effect. In contrast, since the diffraction grating cells12 a to 12 f are different from each other in terms of orientation ofdiffraction grating, the diffraction grating cells 12 a to 12 f havevisual effects different from one another. In other words, the display 1shown in FIG. 10 includes six types of diffraction grating regionshaving different visual effects. Therefore, the diffraction gratingregions of the display shown in FIG. 10 variously change theirappearance according to the observation conditions.

In the display 1 shown in FIG. 10, the light-scattering region 20 a isconstituted by light-scattering cells 21 a in which the orientationaldirection of the light-scattering structure is parallel to the directionthat forms an angle of 45° in counterclockwise direction with respect tothe x direction. The light-scattering region 20 a forms the image of “9”by using light-scattering cells 21 a as pixels. On the other hand, thelight-scattering region 20 b is constituted by light-scattering cells 21b in which the orientational direction of the light-scattering structureis orthogonal to the orientational direction of the light-scatteringstructure included in the light-scattering cells 21 a. Thelight-scattering region 20 b forms a marginal part of the image “9”displayed on the light-scattering region 20 a by using light-scatteringcells 21 b as pixels.

In the light-scattering regions 20 a and 20 b of the display 1 shown inFIG. 10, since the orientational directions of the light-scatteringstructures in the light-scattering cells 21 a and 21 b constituting theregions are orthogonal to each other, the light-scattering axes areorthogonal to each other. Therefore, if the display 1 shown in FIG. 10is illuminated from the direction that forms an angle of 45° incounterclockwise direction with respect to the x direction and observedfrom its front, the scattered light is intensely observed at thelight-scattering region 20 b, whereas the scattered light is notobserved or observed extremely weakly at the light-scattering region 20a. Thus, the image “9” is seen darkly. If the display 1 shown in FIG. 10is illuminated from the direction that forms an angle of 45° inclockwise direction with respect to the x direction and observed fromits front, the scattered light is intensely observed at thelight-scattering region 20 a and the scattered light is not observed orobserved extremely weakly at the light-scattering region 20 b. Thus, animage in which the image “9” is seen whitish and the marginal partthereof is seen darkly is displayed. In other words, the light-and-shadeof the image “9” and the marginal part thereof are reversed every timethe angle of illumination is turned at 90°.

The sizes of the diffraction grating cells 12 a to 12 f and thelight-scattering cells 21 a and 21 b are preferably 300 μm or smaller.In particular, when the display 1 is small, the sizes are preferably 100μm or smaller in consideration of a situation in which the display maybe observed very closely. If the size of each of the cells is equal toor smaller than these numerical values, the cells cannot bedistinguished from each other under the normal observation conditionswith an unaided eye, and enhancement of the forgery-prevention effectand enhancement of the design and decoration can be obtained.

The sizes of the diffraction grating cells 12 a to 12 f and thelight-scattering cells 21 and 21 b are preferably the same. By using thecells having the same size as pixels, the images of the display 1 can beeasily formed from the image data.

As described above, the display 1 shown in FIG. 10 has more complicatedvisual effects than a display which displays an image with one or two ofthe diffraction grating region 10 and the light-scattering regions 20 aand 20 b, since the diffraction grating region 10, which is constitutedby the diffraction grating cells 12 a to 12 f having the orientationsdifferent from one another, and the two light-scattering regions 20 aand 20 b, which are constituted by the respective light-scattering cells21 a and 21 b having the light-scattering axes 27 orthogonal to eachother, separately display images. Therefore, distinction from animitation can be thereby executed with extreme-ease and certainty.

In addition, since the display 1 shown in FIG. 10 forms the images byusing the diffraction grating cells 12 a to 12 f and thelight-scattering cells 21 a and 21 b as pixels, the diffraction gratingand the light-scattering structure for each pixel can be easily arrangedfrom the digital image data, and the images of the display 1 can beeasily made complicated and highly fine. Thus, the visual effect can beenhanced and the forgery-prevention effect is further enhanced.

In addition, since both the diffraction grating 11 and thelight-scattering structure 25 are constituted by protrusions andrecesses, in the display 1 shown in FIG. 10, it can be producedprecisely and easily by merely duplicating the protrusions and recesseswhile maintaining the structures, positional relationship and functionsthereof. As described above, the display 1 produced with high accuracyhas the enhanced reliability on the display as a genuine article, andthe certainty in the authenticity check is enhanced.

Furthermore, even if the display 1 shown in FIG. 10 is to be forged orimitated, the precise structure having these visual effects can hardlybe reproduced exactly. Moreover, the light-scattering structure of thedisplay 1 shown in FIG. 10 cannot be duplicated by an opticalduplication method using the diffracted light from the diffractiongrating 11.

Thus, due to the characteristic visual effects and the difficulty inforgery and imitation, the display 1 shown in FIG. 10 can be thereforeapplied to, for example, securities, cards, passports, etc. as a highsecurity optical medium whose authenticity check can be easily executed.

A modified example of the display 1 shown in FIG. 10 will be described.

FIG. 11 is a plan view schematically showing a modification of thedisplay shown in FIG. 10.

The display 1 shown in FIG. 11 is the same as the display 1 describedwith reference to FIG. 10, except for employing the following structure.In other words, the layer 2 of the display shown in FIG. 11 includes twodiffraction grating regions 10 a and 10 b having orientations differentfrom each other, two light-scattering regions 20 a and 20 b havinglight-scattering axes orthogonal to each other, and the region 30 inwhich the relief structure is not provided.

In the display 1 shown in FIG. 11, the diffraction grating region 10 aconstituted by the diffraction grating cells 12 a forms an image “0”,the diffraction grating region 10 b constituted by the diffractiongrating cells 12 b forms an image “:”, the light-scattering region 20 aconstituted by the light-scattering cells 21 a forms an image “1”, thelight-scattering region 20 b constituted by the light-scattering cells21 b forms an image “9”.

In the display 1 shown in FIG. 11, the light-scattering axis of thelight-scattering region 20 a is approximately orthogonal to that of thelight-scattering region 20 b. Therefore, only one of the images isobserved at a certain observation position and the other image alone isobserved at the other observation positions. In other words, it isimpossible to observe both the images of the light-scattering region 20a and the light-scattering region 20 b.

In addition, in the display 1 shown in FIG. 11, orientation ofdiffraction gratings of the diffraction grating region 10 a is differentfrom that of the diffraction grating region 10 b. Therefore, anobservation position at which the diffraction grating region 10 a isseen iridescently is different from an observation position at which thediffraction grating region 10 b is seen iridescently.

Furthermore, in the display 1 shown in FIG. 11, since relief structuresin the diffraction grating region 10 b and the light-scattering region20 b are oriented in substantially the same directions, both images ofthe regions are observed or the only one of the images is observedaccording to the observation position.

The display 1 shown in FIG. 11 includes the region 30 in which thediffraction grating or the light-scattering structure is not provided.The appearance of the region 30 is not changed according to theobservation position.

As described above, the display 1 shown in FIG. 11 has more complicatedvisual effects than a display in which one or more of these regions areomitted since the two diffraction grating region 10 a and 10 b, whichare constituted by the respective diffraction grating cells 12 a and 12b having the orientations different from each other, and twolight-scattering regions 20 a and 20 b, which are constituted by therespective light-scattering cells 21 a and 21 b having thelight-scattering axes 27 orthogonal to each other, display imagesseparately. Distinction from an imitation can be thereby executed withextremely-ease and certainty.

In addition, since both the diffraction grating 11 and thelight-scattering structure 25 are constituted by protrusions andrecesses in the display 1 shown in FIG. 10, the display 1 can beproduced with accuracy and ease by merely duplicating protrusions andrecesses while maintaining the structures, positional relationship andfunctions thereof. The display 1 produced with stability and highaccuracy has the enhanced reliability on the display as a genuinearticle, and the certainty in the authenticity check is enhanced.

Furthermore, even if the display 1 shown in FIG. 11 is to be forged andimitated, the precise structure having these visual effects can hardlybe reproduced exactly. Moreover, the light-scattering structure of thedisplay 1 shown in FIG. 11 cannot be duplicated by an opticalduplication method using the diffracted light from the diffractiongrating 11.

Thus, due to the characteristic visual effects and the difficulty inforgery and imitation, the display 1 shown in FIG. 11 can be thereforeapplied to, for example, securities, cards, passports, etc. as a highlysecurity optical medium whose authenticity check can be easily executed.

Besides the light scattering-regions 20 a and 20 b including the linearlight-scattering structures, the above-described display 1 may furtherinclude a light-scattering region including protrusions and/or recesseshaving other shapes.

FIGS. 12 and 13 are perspective views schematically showing an exampleof a light-scattering region including protrusions and/or recesseshaving shapes other than the linear shape.

A light-scattering region 20′ shown in FIG. 12 includes protrusions 25 aeach having a shape of a rectangular parallelepiped. An orientationaldirection 26′ of the protrusions 25 a is approximately parallel to xdirection. A light-scattering region 20′ shown in FIG. 13 includesprotrusions 25 b each having a shape of an ellipse. An orientationaldirection 26′ of the protrusions 25 b is approximately parallel to xdirection.

In the light-scattering regions 20′ shown in FIGS. 12 and 13, alight-scattering axis 27′ is approximately parallel to y direction.However, the protrusions 25 a and 25 b included in the light-scatteringregion 20′ shown in FIGS. 12 and 13 have smaller anisotropiclight-scattering ability as compared with the above-described linearprotrusions and/or recesses 25, since the ratio of the dimension in thex direction with respect to the dimension in the y direction is small,for example, within a range of 1 to 5. Therefore, in thelight-scattering regions 20′ shown in FIGS. 12 and 13, the scatteredlight is observed but the change in appearance according to theobservation position is small.

Therefore, the visual effects of the display 1 can be made furthercomplicated by adding the light-scattering region 20′.

The above-described display 1 can also be attached to an article such asa printed articles, etc. and used as a forgery-preventing medium.

FIG. 14 is a plan view schematically showing an example of a labeledarticle which supports the display.

A labeled article 100 shown in FIG. 14 is a magnetic card. The labeledarticle 100 includes a printed substrate 90, and a display 1 supportedby the substrate 90. The display 1 included in the labeled article 100is the above-described display 1.

The labeled article 100 shown in FIG. 14 can be easily distinguishedfrom a non-genuine article since images of the display 1 having thevisual effects of the diffraction grating region and the visual effectof the light-scattering regions and images formed by the printing on thecard 90, i.e., the displayed images constituted by a plurality ofelements having different optical characteristics, can be confirmedvisually. Since the forgery and imitation of the display 1 are difficultas described above, the forgery-prevention effect of the labeled article100 can be expected.

The labeled article shown in FIG. 14 is one of examples of applicationof the display 1, and the application of the display 1 is not limited tothe example of FIG. 14. For example, when the display 1 is applied to anarticle such as a printed article, it may be embedded into paper in theform of thread (also called strip, filament, thread-like object,security band, etc.). In addition, since the display 1 can include anadhesive layer 52 as shown in FIG. 2, it can be easily applied tovarious articles by sticking it onto the various articles.

In addition, it is not necessary that the labeled article is a printedarticle. In other words, the display 1 may be supported by high-gradearticles such as art objects, etc.

The display 1 may be used for the purpose other than theforgery-prevention. For example, it can also be utilized as a toy, ateaching material, a decorative article, etc.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A display comprising light-scattering regionseach provided with linear protrusions or recesses having the samelongitudinal direction, the light-scattering regions being differentfrom each other in the longitudinal direction, and a diffraction gratingregion provided with a relief structure which forms a diffractiongrating.
 2. The display according to claim 1, wherein thelight-scattering regions are in the same plane.
 3. The display accordingto claim 1, wherein the light-scattering regions display images,respectively, and the images are distinguishable from each other with anunaided eye.
 4. The display according to claim 1, wherein each of thelight-scattering regions includes an array of cells, each provided withthe protrusions or recesses.
 5. The display according to claim 4,wherein in at least one of the light-scattering regions, the cellsincluded in the at least one light-scattering region include cellsdifferent from each other in length and/or width of the protrusions orrecesses.
 6. The display according to claim 1, wherein in at least oneof the light-scattering regions, the linear protrusions or recesses arearranged at random.
 7. The display according to claim 1, wherein in atleast one of the light-scattering regions, the linear protrusions orrecesses have the same length and width.
 8. The display according toclaim 1, wherein in at least one of the light-scattering regions, anaverage interval among the protrusion or recesses is equal to or smallerthan 10 μm.
 9. The display according to claim 1, wherein thelight-scattering regions include two light-scattering regions having thelongitudinal directions orthogonal to each other.
 10. The displayaccording to claim 1, further comprising a diffraction grating regionprovided with a relief structure which forms the diffraction grating.11. The display according to claim 10, wherein each of thelight-scattering regions includes an array of cells each provided withthe protrusions or recesses, and the diffraction grating region includesan array of cells each provided with the relief structure.
 12. Thedisplay according to claim 11, wherein in at least one of thelight-scattering regions, the cells included in the light-scatteringregion include cells different in at least one of density, size, shape,and depth or height of the protrusions or recesses, and an area ratio ofa portion provided with the protrusions or recesses with respect to thecell, and the cells included in the diffraction grating region includecells different in at least one of spatial frequency, orientation, anddepth or height of grooves forming the diffraction grating, and an arearatio of the diffraction grating with respect to the cell.
 13. Thedisplay according to claim 1, wherein in at least one of thelight-scattering regions, the protrusions or recesses have planar shapesof circles, ellipses or polygons.
 14. The display according to claim 1,wherein the light-scattering regions are regions included in a mainsurface of a layer made of a light-transmitting material, and thedisplay further comprises a reflective layer or a semitransparentreflective layer covering the main surface.
 15. A labeled articlecomprising: the display according to claim 1; and an article supportingthe display.
 16. The display according to claim 5, wherein in at leastone of the light-scattering regions, the cells included in thelight-scattering region include first and second cells different fromeach other in at least one of length and width of the protrusions orrecesses, the first and second cells being configured to emit thescattered light at first and second degrees of divergence, respectively,such that an image formed by the first and second cells is seen as animage with light and shade.